<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        li {
            list-style: none;
        }

        ul {
            border: 10px solid red;
            width: 80%;
            box-sizing: border-box;
            margin: 0 auto;
            display: table;
        }

        li {
            width: 25%;
            height: 100px;
            float: left;
        }

        li:nth-child(1) {
            background: gray
        }

        li:nth-child(2) {
            background: yellow
        }

        li:nth-child(3) {
            background: black
        }

        li:nth-child(4) {
            background: green
        }
    </style>
</head>

<body>
    <ul>
        <li></li>
        <li></li>
        <li></li>
        <li></li>
    </ul>
</body>

</html>